Classifying machine

ABSTRACT

A classifying machine for sizing articles, separating the articles so sized and delivering those within given size limits to particular bins having a pair of rollers mounted for support on open face bearings. The rollers are raised at the feed end so that the parts move, in part, under the force of gravity toward the discharge end. The rollers are usually tapered outwardly from each other from the feed end toward the discharge end so that the smallest selected sizes of the articles drop between the rollers into a collecting bin at the end nearest the feed end and the articles of the largest size are discharged at or near the discharge end.

United States Patent Cronan Apr. 1, 1975 CLASSIFYING MACHINE Primary Examiner-Allen N. Knowles [75] Inventor. I{ll/after l. Cronan, Palisades Park, Attorney g or Firm samuelson & Jacob [73] Assignee: Volume Products Company, Inc.,

Garfield, NJ. 5 fy h tF F I h c 3581 mg mac me or sizing artlc es, separating t e [22] Med: 1974 articles so sized and delivering those within given size 2 App], 454,973 limits to particular bins having a pair of rollers mounted for support on open face bearings. The rollers are raised at the feed end so that the parts move, [52] U.S. Cl 209/107, 308/DIG. 9 in part, under the force of gravity toward the [51] Int. Cl B071) 13/04 charge The toners are usually tapered outwardly [58] Field Search 209/107 from each other from the feed end tov'vard the dis- 308/DIG' 9 charge end so that the smallest selected sizes of the articles drop between the rollers into a collecting bin [56] References at the end nearest the feed end and the articles of the UNITED STATES PATENTS largest size are discharged at or near the discharge 2.661.090 12/1953 Garrett 209/107 2.960,224 ll/l960 Cronan 3.260364 7/1966 England 209/107 Clam, 17 Drawmg PAIEMEM 1 ms SHEET 3 BF 6 FIG. 8

FIG. 7

PATEHTED APR 1 1975 sumuurg FIG. 9

FIG. IO

CLASSIFY ING MACHINE The invention relates to classifying machines for sizing articles and separating the articles so sized in accordance with a predetermined plan. In particular, the invention is directed toward such a machine wherein the classifying is carried on between a pair of rollers which are usually outwardly tapered from each other so that the smallest articles drop between the rollers near the feed end of the machine. The rollers in the machine of the invention are driven at their feed ends and rest at both the feed and the discharge ends on pairs of bearings preferably mounted in substantially perpendicular planes so that the rollers are supported on their surfaces rather than on their axes.

Prior art classifying machines use rollers which are mounted on their axes so that it is necessary for three dimensions to be as accurate as possible, namely, centerline straightness, surface circularity and surface straightness. As a consequence, it is very important that such rollers be accurately machined and checked periodically to be certain that the accuracy is being maintained.

It is an important object of the invention to provide a classifying machine which maintains its accuracy while being simple to operate and maintain.

It is a further object of the invention to provide such a machine wherein the rollers are mounted on bearings in Contact with their surfaces rather than being mounted on their central axes.

It is another object of the invention to provide such a machine wherein the position of a roller is adjustable with respect to its support bearings to facilitate compensation due to surface wear.

It is a still further object of the invention to provide an auxiliary bearing to further preclude movement of the roller out of its engaged position.

It is yet another object of the invention to provide an improved collecting bin for use with classifying machines of the invention.

These and other objects, advantages, features and uses will be apparent during the course of the following description when taken in conjunction with the accompanying drawing.

Broadly, the invention comprises a classifying machine having a pair of oppositely rotating rollers spaced outwardly from each other. The surfaces of the rollers are supported on bearings at the feed and discharge ends of the machine so that it is not necessary to maintain the accuracy of the axes of rotation within close tolerances in order to obtain accurate sizing of the articles being classified. The sized articles are collected in bins or other collectors in accordance with a predetermined plan as dictated by the particular requirements of the user of the articles.

Due to the manner in which the rollers are supported, the two inwardly-facing portions of the rollers are free of obstruction throughout their length. This facilitates the passage of the articles being classified and enables use of substantially the total roller length. This is not possible when ordinary journal bearings are used. Moreover, ordinary journals require the entire bearing mounting to be rotated when angular adjustments are made. Since the bearings are fixed in position during operation, adjustments of the roller positions may be made while they are in motion. The forces generated during rotation of the rollers urge the rollers against the bearings to thereby keep them in their operating positions. Prior art, spring loaded, centerline supported rollers had to be relieved in a sidewise direction which frequently resulted in wholesale dumping of the articles being classified and contaminated measurements and separations. No such relief is needed in the present construction so that wholesale dumping and contamination are avoided.

In the accompanying drawing, forming a part of this application, and in which like numerals are employed to designate like parts throughout the same:

FIG. I is a perspective view of a machine of the invention;

FIG. 2 is an enlarged, elevational view of a roller used with the machine of FIG. 1;

FIG. 3 is an elevational view of the roller of FIG. 2 installed in the machine;

FIG. 4 is an end elevational view, somewhat enlarged, of the feed end of the machine, showing the roller support bearings;

FIG. 4A is an end view of a roller showing a movable wedge for raising and/or lowering the end of the roller;

FIG. 5 is an end elevational view, somewhat enlarged, showing the drive gears for rotating the rollers of the machine of FIG. 1;

FIG. 6 is an enlarged plan view showing the means for adjusting the lateral spacing between the rollers of FIG. 1;

FIG. 7 is a sectional view taken on lines 7-7 of FIG. 6, viewed in the direction of the arrows;

FIG. 8 is a sectional view taken on lines 8-8 of FIG. 6, viewed in the direction of the arrows;

FIG. 9 is an enlarged, elevational view of the roller drive mechanism of the machine of FIG. 1',

FIG. 10 is an enlarged, plan view of the roller drive mechanism of the machine of FIG. 1',

FIG. II is an enlarged, elevational view of the elevating mechanism of the machine of FIG. 1;

FIG. 12 is a sectional view taken on lines l2I2 of FIG. 11, viewed in the direction of the arrows;

FIG. 13 is a sectional view taken on lines I3l3 of FIG. 11, viewed in the direction of the arrows;

FIG. 14 is an enlarged, plan view of a collecting hopper for use with the machine of FIG. 1;

FIG. 15 is a side elevational view, partly in section, of the collecting hopper of FIG. 14, showing the exit opening closed; and

FIG. 16 is a view similar to FIG. 15 showing the collecting hopper with its exit opening open.

In the drawing, wherein, for the purpose of illustration, are shown specific embodiments of the invention, the numeral 20 designates a classifying machine of the invention, generally. Machine 20 is seen to comprise (FIG. I) a feed end 22, a discharge end 24, roller 26 which is fixed in position, and roller 28 which is movable transversely with respect to roller 26. A hand wheel 32 is provided to regulate and adjust the height of the feed end 22 and a hand wheel 30 is used to simultaneously adjust the transverse position of both ends of roller 28 with respect to roller 26 (coarse adjustment). A hand wheel 34 is used to make the separate fine adjustment of the roller spacing at the feed end 22 and a similar hand wheel 36 is used for the separate fine adjustment at the discharge end 24. Gauges 38 and 40 are provided to enable the user to measure and adjust the relative transverse spacing of the corresponding roller ends of the two rollers accurately.

Normally. the ends of the rollers at the discharge end of the machine are further apart than at the feed end. However, if the particular task assigned to the machine is to separate all articles above a certain size from all those below that size, the rollers may be equally spaced throughout their length so that the smaller articles drop through between the rollers and the large ones leave the machine at the discharge end. Since the usual operation of the machine requires separations into several different sizes, the discussion hereafter will assume that the discharge ends of the rollers are further apart than are the free ends (defined herein as having the rollers outwardly tapered).

In FIG. 2 there is illustrated a roller 26 or 28. The rollers 26 and 28 are provided, respectively, with a driven gear 40 and 42 at the feed end and a center support pad 44 and 46 at the discharge end. Driven gears 40 and 42 are driven, respectively, by drive gears 48 and 50. The gears are preferably 45 helical spiral or spur gears so that the rotational forces tend to keep the rollers in operative position as has been discussed above.

A ball 52 is provided in each support block 25 and 27 and bears against the associated center support pad 44 or 46. Ball 52 is mounted on the end of a rod 54 whose position is adjusted by means of a screw 56 and when the desired position is reached, it is locked in position by means of set screw 58. Thus, it can be seen that the longitudinal position of the roller may be adjusted a slight amount to accommodate for surface wear at the bearing contact points. The amount of such adjustment is limited by the meshing characteristics of the drive and driven gears.

The ends of the rollers 26 and 28 are respectively supported on their surfaces by bearings 60, 62 and 64, 66. These bearings are preferably formed as cylinders of technical carbon graphite having good dry bearing and wear characteristics. No lubrication need be applied to these bearings as the moisture in the air is sufficient. By supporting the rollers on their surfaces, one is enabled to produce the rollers much more easily than rollers which are supported on their central axis. Only 2 of accuracy are required namely, roundness and straightness. The accuracy of these two parameters makes for accurate rotation about the roller axis because there is no transfer error since the roller surface is its own bearing.

The bearings 60 and 62 and 64 and 66 are mounted in intersecting planes in the support blocks 23, 25 and 27, 29, preferably at right angles and the rotation of the roller exerts a force to urge the roller toward the bearings. In some installations, it is advisable that a third bearing 68 or 70 be provided for safety purposes. It is preferably spring biased as shown at 69 and 71 in FIG. 4 and is also formed of technical carbon graphite. The auxiliary bearing 70 or 68 is located in the quandrant opposite that contained between the surface bearings 60, 62 or 64, 66 and prevents the roller from being dislodged when it is struck, as for example, by the operators elbow.

In FIG. 4A, there is shown a view similar to that of FIG. 4 of the discharge end of roller 26. A movable wedge 65 is suitably mounted on block 25 so that it may be moved from right to left in the figure (the mounting details do not form a part of the invention and are not shown). It can be seen that as the wedge is moved to the right, the end of the roller is raised and as it is moved to the left, the end of the roller is dropped. Thus, the rollers may be levelled with respect to each other. While one such movable wedge is usually sufficient, certain systems may require that all four roller ends be provided with such height adjusting mechanisms.

FIG. 5 shows the rotation of the drive and driven gears and illustrates that the rollers rotate in an outward direction so that the articles riding in the nip between the rollers are urged upward against the force of gravity.

In FIG. 6 there is shown the coarse and fine transverse spacing adjustments. Handle 30 is connected by a rod 76 to a pair of worms 78 and 80 mounted thereon. Gears 78 and 80 are respectively engaged in worm gears 82 and 84 which are mounted on a common shaft with pinions 83 and 83', respectively. Pinions 83 and 83' mesh with racks 86 and 88, respectively. Rack 86 is contained in guide bar and rack 88 is contained in guide bar 92. As handle 30 is turned, worms 78 and 80 rotate to turn worm gears 82 and 84 and pinions 83 and 83' to thereby move racks 86 and 88 which are suitably connected to support blocks 27 and 29 and thus move roller 28 transversely with respect to roller 26.

The mounting of the rack 88 is similar to that of rack 86 so that the following discussion with respect to rack 86 also applies to rack 88. Rack 86 is held in the recess in guide bar 90 by a pair of studs 91 which prevents the rack from dropping down. Spring biased screw and ball 93 serves to press the rack into contact with its associated pinion. Set screw 95 is loosened to permit the rack to move when the coarse adjustment wheel 30 is turned and is tightened down to hold the rack fixed after the coarse adjustment is made.

A helical gear is caged in block 27 and is threaded on rod 101. Rod 10] is affixed to an arm 103 which is fastened to the end of rack 86. Thus, when racks 86 and 88 are moved, the support blocks 27 and 29 are also moved with respect to support blocks 23 and 25.

The fine transverse adjustments for the ends of roller 28 are accomplished separately and the discussion for that at the discharge end applies equally to that at the feed end. Handle adjustment 36 is mounted on a rod 96 to which there is affixed a spur gear 98. Spur gear 98 is engaged in helical gear 100 which is mounted on threaded rod 101. Gear I00 is caged in support 27 so that as the handle 36 is moved, support block 27 is moved along threaded rod 101 to thereby move the end of roller 28 with respect to the same end of roller 26. To lock support 27 in position, a lever arm 104 bears against a spring biased rod 106 to hold the rack 86 locked as shown in FIG. 8. Now, if handle 36 is accidently moved, it will not move the support block 27. When lever arm 104 is moved in the direction of the arrow of FIG. 8, the spring 108 relaxes and the rack 86 is unlocked so that control is in the handles 30, 34 and 36. It is not always necessary to use the locking features of screws 95 and handles 104 but they serve to help hold the desired setting to within very fine tolerances.

The fine adjustments may be accurately reproduced by using the dial indicators shown in FIG. 1. The construction permits use of a medium sized, short range indicator (0.050 inch) to produce the effect of an indicator with a 2 inch range. The dial indicator 40 is mounted on a rod 109 or similar support mounted on the frame of the machine. A pad 112 is movably mounted on a fixed rod 111 which is affixed to support block 27. Pad 112 is moved toward indicator until it contacts a feeler which is affixed to indicator 40. Now, a value is read on the indicator 40. As handle 36 is rotated the value on the indicator dial changes and it is then possible to read the movement of block 27 with respect to block 25 very accurately, for example, to a ten-thousandth of an inch.

FIGS. 9 and 10 illustrate the drive mechanism used to drive drive gears 48 and 50. A motor is mounted to a frame 122 and is held in place by a spring 124 under tension. This permits the motor to move when block 29 is moved so that the toothed drive belt 128 is always tight. A gear 126 is attached to the motor shaft to drive belt 128. In turn, gear 130 is rotated in the direction shown by the arrow. Gear 130 and gear 50 are mounted on a common shaft 131 so that gear 50 rotates and drives gear 42 and roller 28.

An idler 132 serves to keep the belt tight. A gear 134 and a gear 136 are mounted on a common shaft 135 so that gear [36 rotates as gear 134 is rotated by the belt 128. Gear 136 is meshed with a gear 138 which is mounted on a common shaft 139 with gear 48. The gear rotations shown in FIG. 9 will produce the desired rotation of rollers 26 and 28.

It is also possible to accomplish the desired result by mounting the motor in a fixed position in the frame and mounting idler 132 to a spring affixed to the frame to thereby compensate for any movement of block 29.

FlGS. ll-l3 illustrate the mechanism used to raise the feed end of the machine. Handle 32 is mounted on a rod on the end of which there is mounted a gear 152 which is engaged in a gear [54 mounted on a rod 156. Two pinion gears 158 and are mounted on rod 156 which is affixed to the machine housing. The pinion gears 158 and 160 are engaged in racks 162 and 164, respectively. The racks rest on the floor so that as the handle 32 is turned the feed end of the machine is moved vertically to place it at the desired level to produce the required descent angle for the articles being processed by the machine. Racks 162 and 164 are forced outwardly against a pair of opposed ledges 165 by a fixed rod 163. This holds the racks in position.

FlGS. 1446 illustrate a collection bin or hopper to be used with the machine of FlGS. l-l3. Hopper 180 is seen to comprise an open top 182 to permit articles dropped between the rollers to enter the hopper, two straight vertical sides 184 and 186 to allow a plurality of hoppers to he placed side by side as shown in FIG. 1 and two slanted sides 188 and 190 to permit the articles to collect at the bottom of the bin. Side 190 is provided with an opening 192 which may be closed by means of door 194 or left open by moving door 194 to the position of FIG. 16. Door 194 is affixed to flat strip 196 which may be held in place in the two desired positions as shown in FIGS. 15 and 16. When door 194 is in the position of FIG. 16, a pipe 198 or other unit is affixed as shown to permit the articles to drop into another larger bin or other receptacle. The position of FIG. 15 is generally used for relatively low volume runs where supervision and personnel for emptying the hopper are available and that of FIG. 16 is generally used for high volume runs to avoid the frequent need for personnel to empty the hopper.

Operation of the machine of the invention is economical and simple. The spacing of the rollers is adjusted to accommodate for the sizes to be classified and the feed end is raised to the desired height. The articles are dropped between the rollers near the feed end and proceed down the rollers. As soon as an article has clearance between the rollers it drops into the bin at that point. Even though high production speeds are readily attained, a single attendant has no difficulty in keeping the bins of several machines emptied and ready to receive additional articles. In fact, under many operating conditions, the machine may run accurately for long periods without any human supervision.

While particular embodiments of the invention have been shown and described, it is apparent to those skilled in the art that modifications are possible without departing from the spirit of the invention or the scope of the subjoined claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. in a classifying machine for sizing articles and separating the articles so sized in a predetermined pattern having a feed end and a discharge end, a pair of rollers higher at the feed end than at the discharge end and spaced with respect to each other, and drive means for rotating the rollers in opposite directions, the improvement comprising:

four pairs of bearings mounted at the ends of the rollers to support the rollers at the ends, each such pair supporting one end of one of said rollers;

the bearings of each pair being mounted in intersecting planes to thereby bear against the outer surface of the roller associated with the said pair of bearings such that the forces applied by the bearings are in a direction toward the other roller;

a pair of drive gears mounted at the feed end, there being one drive gear associated with each roller; and a driven gear mounted on the feed end of each roller engaging the associated drive gear;

the drive gears being rotated by the drive means so that the rollers are rotated in opposite directions and are urged outwardly toward the pairs of bearings.

2. The invention of claim 1 including:

means for simultaneously moving both ends of one roller transversely with respect to the other roller; and

means for selectively moving each end of the one roller transversely with respect to the other roller.

3. The invention of claim 2 including:

auxiliary bearing means mounted at the end of and near the top of one of the rollers such that the force exerted thereby is away from the other roller.

4. The invention of claim 1 including:

auxiliary bearing means mounted at the end of and near the top of one of the rollers such that the force exerted thereby is away from the other roller.

5. The invention of claim 4 including:

means for locking the end of the movable roller in position.

6. The invention of claim 3 including:

means for locking the end of the movable roller in position.

7. The invention of claim 2 including:

means for locking the end of the movable roller in position.

8. The invention of claim 2 including:

means for moving the feed end of the machine vertically.

9. The invention of claim 8 including:

collecting means placed below the rollers for receiving articles of a predetermined size therein.

10. The invention of claim 7 including:

collecting means placed below the rollers for receiving articles of a predetermined size therein.

11. The invention of claim 6 including:

collecting means placed below the rollers for receiving articles of a predetermined size therein.

12. The invention of claim including:

collecting means placed below the rollers for receiving articles of a predetermined size therein.

13. The invention of claim 4 including:

collecting means placed below the rollers for receiving articles of a predetermined size therein.

14. The invention of claim 3 including:

collecting means placed below the rollers for receiving articles of a predetermined size therein.

15. The invention of claim 2 including:

collecting means placed below the rollers for receiving articles of a predetermined size therein.

16. The invention of claim 1 including:

collecting means placed below the rollers for receiving articles of a predetermined size therein.

17. The invention of claim 16 including:

means for adjusting the longitudinal position ofa roller with respect to the pair of bearings associated with the said roller.

18. The invention of claim including:

means for adjusting the longitudinal position ofa roller with respect to the pair of bearings associated with the said roller.

19. The invention of claim 14 including:

means for adjusting the longitudinal position of a roller with respect to the pair of bearings associated with the said roller.

20. The invention of claim 13 including:

means for adjusting the longitudinal position ofa roller with respect to the pair of bearings associated with the said roller.

2!. The invention of claim 12 including:

means for adjusting the longitudinal position of a roller with respect to the pair of bearings associated with the said roller.

22. The invention of claim 11 including:

means for adjusting the longitudinal position of a roller with respect to the pair of bearings associated with the said roller.

23. The invention of claim 10 including:

means for adjusting the longitudinal position of a roller with respect to the pair of bearings associated with the said roller.

24. The invention of claim 9 including:

means for adjusting the longitudinal position of a roller with respect to the pair of bearings associated with the said roller.

25. The invention of claim 8 including:

means for adjusting the longitudinal position of a roller with respect to the pair of bearings associated with the said roller.

26. The invention of claim 7 including:

means for adjusting the longitudinal position of a rol ler with respect to the pair of bearings associated with the said roller.

27. The invention of claim 6 including:

means for adjusting the longitudinal position of a roller with respect to the pair of bearings associated with the said roller.

28. The invention of claim 5 including:

means for adjusting the longitudinal position of a roller with respect to the pair of bearings associated with the said roller.

29. The invention of claim 4 including:

means for adjusting the longitudinal position of a roller with respect to the pair of bearings associated with the said roller.

30. The invention of claim 3 including:

means for adjusting the longitudinal position ofa roller with respect to the pair of bearings associated with the said roller.

31. The invention of claim 2 including:

means for adjusting the longitudinal position of a roller with respect to the pair of bearings associated with the said roller.

32. The invention of claim 1 including:

means for adjusting the longitudinal position ofa roller with respect to the pair of bearings associated with the said roller.

* l k =l 

1. In a classifying machine for sizing articles and separating the articles so sized in a predetermined pattern having a feed end and a discharge end, a pair of rollers higher at the feed end than at the discharge end and spaced with respect to each other, and drive means for rotating the rollers in opposite directions, the improvement comprising: four pairs of bearings mounted at the ends of the rollers to support the rollers at the ends, each such pair supporting one end of one of said rollers; the bearings of each pair being mounted in intersecting planes to thereby bear against the outer surface of the roller associated with the said pair of bearings such that the forces applied by the bearings are in a diRection toward the other roller; a pair of drive gears mounted at the feed end, there being one drive gear associated with each roller; and a driven gear mounted on the feed end of each roller engaging the associated drive gear; the drive gears being rotated by the drive means so that the rollers are rotated in opposite directions and are urged outwardly toward the pairs of bearings.
 2. The invention of claim 1 including: means for simultaneously moving both ends of one roller transversely with respect to the other roller; and means for selectively moving each end of the one roller transversely with respect to the other roller.
 3. The invention of claim 2 including: auxiliary bearing means mounted at the end of and near the top of one of the rollers such that the force exerted thereby is away from the other roller.
 4. The invention of claim 1 including: auxiliary bearing means mounted at the end of and near the top of one of the rollers such that the force exerted thereby is away from the other roller.
 5. The invention of claim 4 including: means for locking the end of the movable roller in position.
 6. The invention of claim 3 including: means for locking the end of the movable roller in position.
 7. The invention of claim 2 including: means for locking the end of the movable roller in position.
 8. The invention of claim 2 including: means for moving the feed end of the machine vertically.
 9. The invention of claim 8 including: collecting means placed below the rollers for receiving articles of a predetermined size therein.
 10. The invention of claim 7 including: collecting means placed below the rollers for receiving articles of a predetermined size therein.
 11. The invention of claim 6 including: collecting means placed below the rollers for receiving articles of a predetermined size therein.
 12. The invention of claim 5 including: collecting means placed below the rollers for receiving articles of a predetermined size therein.
 13. The invention of claim 4 including: collecting means placed below the rollers for receiving articles of a predetermined size therein.
 14. The invention of claim 3 including: collecting means placed below the rollers for receiving articles of a predetermined size therein.
 15. The invention of claim 2 including: collecting means placed below the rollers for receiving articles of a predetermined size therein.
 16. The invention of claim 1 including: collecting means placed below the rollers for receiving articles of a predetermined size therein.
 17. The invention of claim 16 including: means for adjusting the longitudinal position of a roller with respect to the pair of bearings associated with the said roller.
 18. The invention of claim 15 including: means for adjusting the longitudinal position of a roller with respect to the pair of bearings associated with the said roller.
 19. The invention of claim 14 including: means for adjusting the longitudinal position of a roller with respect to the pair of bearings associated with the said roller.
 20. The invention of claim 13 including: means for adjusting the longitudinal position of a roller with respect to the pair of bearings associated with the said roller.
 21. The invention of claim 12 including: means for adjusting the longitudinal position of a roller with respect to the pair of bearings associated with the said roller.
 22. The invention of claim 11 including: means for adjusting the longitudinal position of a roller with respect to the pair of bearings associated with the said roller.
 23. The invention of claim 10 including: means for adjusting the longitudinal position of a roller with respect to the pair of bearings associated with the said roller.
 24. The invention of claim 9 including: means for adjusting the longitudinal position of a roller with respect to the pair of bearings associated with the said roller.
 25. The invention of claim 8 including: means for adjusting the longitudinal position of a roller with respect to the pair of bearings associated with the said roller.
 26. The invention of claim 7 including: means for adjusting the longitudinal position of a roller with respect to the pair of bearings associated with the said roller.
 27. The invention of claim 6 including: means for adjusting the longitudinal position of a roller with respect to the pair of bearings associated with the said roller.
 28. The invention of claim 5 including: means for adjusting the longitudinal position of a roller with respect to the pair of bearings associated with the said roller.
 29. The invention of claim 4 including: means for adjusting the longitudinal position of a roller with respect to the pair of bearings associated with the said roller.
 30. The invention of claim 3 including: means for adjusting the longitudinal position of a roller with respect to the pair of bearings associated with the said roller.
 31. The invention of claim 2 including: means for adjusting the longitudinal position of a roller with respect to the pair of bearings associated with the said roller.
 32. The invention of claim 1 including: means for adjusting the longitudinal position of a roller with respect to the pair of bearings associated with the said roller. 